• Title/Summary/Keyword: Leaf disease

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Application of Bacterial Endophytes to Control Bacterial Leaf Blight Disease and Promote Rice Growth

  • Ooi, Ying Shing;Nor, Nik M.I. Mohamed;Furusawa, Go;Tharek, Munirah;Ghazali, Amir H.
    • The Plant Pathology Journal
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    • v.38 no.5
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    • pp.490-502
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    • 2022
  • Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

Machine Vision Based Detection of Disease Damaged Leave of Tomato Plants in a Greenhouse (기계시각장치에 의한 토마토 작물의 병해엽 검출)

  • Lee, Jong-Whan
    • Journal of Biosystems Engineering
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    • v.33 no.6
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    • pp.446-452
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    • 2008
  • Machine vision system was used for analyzing leaf color disorders of tomato plants in a greenhouse. From the day when a few leave of tomato plants had started to wither, a series of images were captured by 4 times during 14 days. Among several color image spaces, Saturation frame in HSI color space was adequate to eliminate a background and Hue frame was good to detect infected disease area and tomato fruits. The processed image ($G{\sqcup}b^*$ image) by OR operation between G frame in RGB color space and $b^*$ frame in $La^*b^*$ color space was useful for image segmentation of a plant canopy area. This study calculated a ratio of the infected area to the plant canopy and manually analyzed leaf color disorders through an image segmentation for Hue frame of a tomato plant image. For automatically analyzing plant leave disease, this study selected twenty-seven color patches on the calibration bars as the corresponding to leaf color disorders. These selected color patches could represent 97% of the infected area analyzed by the manual method. Using only ten color patches among twenty-seven ones could represent over 85% of the infected area. This paper showed a proposed machine vision system may be effective for evaluating various leaf color disorders of plants growing in a greenhouse.

Alternative Measure for Assessing Incidence of Leaf Stripe on Barley

  • Arabi, Mohammad Imad Eddin;Jawhar, Mohammad
    • The Plant Pathology Journal
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    • v.28 no.2
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    • pp.212-215
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    • 2012
  • Pyrenophora graminea, the causal agent of leaf stripe disease, is an economically important pathogen of barley found worldwide. It is critical to clearly define and standardize the leaf stripe assessment methods to avoid subjectivity and variability between assessors. Therefore, in this study, a comparison between the proportion of diseased plants (DP) and the proportion of diseased leaves (DL) per plant was investigated. Disease assessments were made visually at multiple sample sites in artificially and naturally inoculated research and production fields during four growing seasons. There were significant differences (P = 0.001) among cultivars in mean DP and DL averages, which are consistently higher in susceptible barley. However, DP values increased linearly as DL increased. The slopes and intercepts of the DP-DL relationship were consistent over the four growing seasons. This result might make a significant contribution for leaf stripe assessment in barley breeding programme.

First Report of Fusarium subglutinans Causing Leaf Spot Disease on Cymbidium Orchids in Korea

  • Han, Kyung-Sook;Park, Jong-Han;Back, Chang-Gi;Park, Mi-Jeong
    • Mycobiology
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    • v.43 no.3
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    • pp.343-346
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    • 2015
  • In 2006~2010, leaf spot symptoms, that is, small, yellow spots that turned into dark brown-to-black lesions surrounded by a yellow halo, were observed on Cymbidium spp. in Gongju, Taean, and Gapyeong in Korea. A Fusarium species was continuously isolated from symptomatic leaves; in pathogenicity testing, isolates caused leaf spot symptoms consisting of sunken, dark brown lesions similar to the original ones. The causal pathogen was identified as Fusarium subglutinans based on morphological and translation elongation factor 1-alpha sequence analyses. This is the first report of F. subglutinans as the cause of leaf spot disease in Cymbidium spp. in Korea.

Cultural Characteristics of Mcyosphaerella nawae causing Spotted Leaf Casting of Persimmon (감나무 둥근무늬낙엽병균(Mycosphaerella nawae)의 배양적 특성)

  • 권진혁;강수웅;정부근;박창석
    • Plant Disease and Agriculture
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    • v.1 no.2
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    • pp.18-21
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    • 1995
  • Mycosphaerella nawae, the causal organism, of spotted leaf casing disease of persimmon, was isolated from infected leaves showing typical symptom. The cultural characteristics of the fungus were compared on artificial media. Among 24 different combinations of culture media and supplements, oatmeal agar+persimmon leaf extract (PLE) and PAD+ PLE+streptomycin showed the highest rate of isolating as 57.1%. The best medium for mycelial growth of the fungus was PDA+persimmon leaf powder (PLP). The colony diameter was reached 47mm for 30 days at 2$0^{\circ}C$. PDA+PLE also supported good mcyelial growth showing 46mm of diameter in same condition. The optimum growth temperature of this fungus in PDA was recognized fairly low. The mycelial growth was higher at 2$0^{\circ}C$ than 15$^{\circ}C$. The variation of pH between pH 4 to pH 8 did not affect to the mycelial growth of the pathogen.

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First Report of Leaf Spot in Water Spinach Caused by Ectophoma multirostrata

  • Gyo-Bin Lee;Hong-Sik Shim;Weon-Dae Cho;Wan-Gyu Kim
    • The Korean Journal of Mycology
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    • v.50 no.4
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    • pp.367-372
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    • 2022
  • Leaf spot symptoms were observed in water spinach (Ipomoea aquatica) plants growing in fields in Ansan and Hongseong, Korea, during disease surveys in 2019 and 2020. The symptoms appeared as brown to dark brown circular or irregular spots on the leaves of the plants. The disease incidence on the plant leaves in the fields investigated at the two locations ranged from 1% to 20%. Five single-spore isolates of Phoma sp. Were obtained from lesions of the diseased leaves. All the isolates were identified as Ectophoma multirostrata based on their cultural and morphological characteristics, as well as molecular analysis. Two isolates of E. multirostrata were tested for pathogenicity on water spinach leaves using artificial inoculation. The tested isolates caused leaf spot symptoms in the inoculated plants. These symptoms were similar to those observed in plants from the investigated fields. To our knowledge, this is the first report of E. multirostrata causing leaf spot in water spinach.

Didymella gigantis sp. nov. Causing Leaf Spot in Korean Angelica

  • Gyo-Bin Lee;Ki Deok Kim;Weon-Dae Cho;Wan-Gyu Kim
    • Mycobiology
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    • v.51 no.6
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    • pp.393-400
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    • 2023
  • During a disease survey in October 2019, leaf spot symptoms with a yellow halo were observed on Korean angelica (Anglica gigas) plants grown in fields in Pyeongchang, Gangwon Province, Korea. Incidence of diseased leaves of the plants in the investigated fields ranged from 10% to 60%. Morphological and cultural characteristics of two single-spore isolates from the leaf lesions indicated that they belonged to the genus Didymella. Molecular phylogenetic analyses using combined sequences of LSU, ITS, TUB2, and RPB2 regions showed distinct clustering of the isolates from other Didymella species. In addition, the morphological and cultural characteristics of the isolates were somewhat different from those of closely related Didymella spp. Therefore, the novelty of the isolates was proved based on the investigations. Pathogenicity of the novel Didymella species isolates was confirmed on leaves of Korean angelica plants via artificial inoculation. This study reveals that Didymella gigantis sp. nov. causes leaf spot in Korean angelica.

Dispersal of Xanthomonas axonopodis pv. citri, the Causal Bacterium of Citrus Canker, on Unshiu Orange.

  • Myung, Inn-Shik;Nam, Ki-Woong;Kwon, Hyeog-Mo
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • 2003.10a
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    • pp.121.1-121
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    • 2003
  • Dispersal of Xanthomonas axonopodis pv. citri, causing citrus bacterial canker disease on Unshiu orange was investigated at previously infested plots at Seogwipo in Jeju island of Korea. The bacterial pathogen overwintered in lesions started to multiply at tate May, and disease firstly observed one month after detection of phage from lesions. The disease gradually increased, however, it dispersed non-directionally to nearby plants from inoculum sources. Diseased plants were aggregated to form a cluster throughout the experiment. Population dynamics of phage on symtomless leaf surface and the disease severity were compared in the nursery, Increase of phage population on symptomless leaf surface preceded one month to that of the disease severity Population of phage increased constantly from late July to October, however, the disease severity decreased from late August to late October. It was assumed that the decrease of disease severity might be due to disease-induced defoliation.

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Effects of Seed Disinfectant Treatments on Leaf Blight and Smut Disease in Coix lacryma-jobi L. var. ma-yuen Stapf (율무 잎마름병과 깜부기병에 대한 종자소독 효과)

  • Chang, Seog-Won;Kim, Hee-Dong;Jeon, Dae-Hoon
    • Korean Journal of Medicinal Crop Science
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    • v.8 no.1
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    • pp.79-82
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    • 2000
  • This study was carried out to investigate the effect of seed disinfectant on leaf blight and smut in adlay. Leaf blight and smut disease in adlay are known to be seed borne. Bjpolan's cojds, pathogen causing leaf blight in adlay, was detected from 32. 7 to 45. 7 % on seeds collected from adlay cultivated farms in Yonchon province. Periods of seed infestation are $0{\sim}7$ days on the variety 'yulmu 1' and $0{\sim}20$ days on 'Yonchon jaerae'. Distribution ratio of seed disinfestation periods was that no disinfestation, $1{\sim}5$days, $6{\sim}10$days and more 11days were 20%, 20%, 45% and 15%, respectively. Frudioxonil W. S. treatment was effective on inhibition of leaf blight and smut disease when treated with infested seeds ; that is, disease control values of the fungicide are 97 and 93.4 percentage, repectively.

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First Report of Leaf Spot Disease on White Chrysanthemum (Chrysanthemum morifolium) Caused by Epicoccum sorghinum in Korea (Epicoccum sorghinum에 의한 국화 점무늬병 발생)

  • Sieun Kim;Jong-Hwan Shin;Ha-Kyoung Lee;Seong-Chan Lee;You-Kyoung Han
    • Research in Plant Disease
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    • v.30 no.3
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    • pp.283-287
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    • 2024
  • In September 2023, a leaf spot disease occurred on chrysanthemum (Chrysanthemum morifolium) in Imsil-gun Agricultural Technology Center, Korea. A fungal species was isolated from the diseased plant and identified as an ascomycete Epicoccum sorghinum based on morphological characteristics and phylogenetic analyses using the sequences of the ITS, TUB2, and ACT genes. A pathogenicity test revealed that the isolate was the causal agent of leaf spot disease on chrysanthemum. This is the first report of leaf spot disease caused by E. sorghinum on chrysanthemum in Korea.